Migrating a Legacy Application to a Service-Oriented Architecture (SOA) Guide
Staying up to date and relevant is the essential task of any business, entrepreneur, product owner, etc., that wants to “stay afloat” in the current market conditions. When it comes to software, especially business systems, user demands are ever-growing and fast to be satisfied by your competitors. To meet the common performance standards and evolve along with their demands, you should regularly upgrade and improve your legacy software.
And migrating from legacy to SOA — Service-Oriented Architecture — may as well just be the most efficient and versatile method to do that. In turn, neglecting legacy architecture modernization, migration, or, simply put, re-architecting, you are definitely not learning from the mistakes of others. A whole airport system once crashed due to a harshly outdated OS and rigid structure, while 90% of businesses right now are limited in system expansion opportunities due to a heavy dependency on their legacy software.
So let’s figure out architecture-driven migration of legacy systems to cloud-enabled software — why you need it, what you will get out of it, and how to do it best.
What is Service-Oriented Architecture (SOA)?
Service-Oriented Architecture is a unique style of software design where complex systems are segmented into services delivered over communication protocols for ultimately more convenient, easier to maintain, and smoother performance.
On top of that, this paradigm outlines the essential values and properties that an SOA product must focus on:
- Concrete business values rather than separate technical specifics.
- Strategic goals rather than advantages specific to a project.
- Intrinsic interoperability rather than custom integrations.
- Shared services rather than narrowly-directed implementations.
- Flexibility rather than endless optimization.
- Evolutionary refinement rather than the search for perfection from the very project kick-off.
These are all outlined in the SOA manifesto that was published back in 2009.
The main field of application and practice of SOA methods is the business software niche. The whole paradigm serves the ultimate purpose of making business systems more manageable, convenient, and reliable overall by breaking down complex applications into easier-to-handle chunks.
And this is exactly where a great use for legacy system architecture modernization arises. In particular, legacy solutions with a monolithic structure can be efficiently transformed into more versatile, smoother running, and easier to maintain systems set in motion by the microservices-based foundation. With the SOA approaches, many businesses nowadays manage to preserve performance and improve without losing some core assets.
Benefits of SOA-Driven Software Modernization Projects
The main benefits of moving your legacy application architecture to the SOA format are unprecedented. Namely, you are looking at revamping the old clunky monolith software by making it more dynamic and based on the separate logically structured moving parts.
Services reusability
Migration to SOA lets one start reusing certain underlying services to one’s heart’s content or even turning them into public third-party use assets. This allows for saving significant costs in enterprises big and small.
The main thing is to outline legacy to new architecture patterns so as not to overly complicate the legacy assets and functions in their updated form (which may happen when your modernization vendor overdoes their job when rebuilding certain things from scratch).
Services scalability
The question of continuous scalability can be handled much more efficiently with SOA approaches. Thus, all you need to do is create more instances of certain services to handle the growing accumulation of data. As the load on your system increases, you simply add more bricks to handle “more weight.” This is an essential advantage of a services-based architecture.
Compare this to the bulky, cumbersome nature of monolithic systems where you simply cannot scale up separate software elements. The only way to go is to expand the whole application, which ultimately results in higher memory consumption, intenser I/O traffic, and lower efficiency of caching.
Tech independence and loose coupling
The implementation of loose coupling in SOA systems along with the complete independence from technologies — these two factors make SOA solutions so much more flexible and rich with potential. In particular, developers can add new essential features really fast and easily, saving lots of time and budget.
As opposed to that, monolithic legacy solutions are characterized by tight coupling and have interconnected modules. This really complicates one’s attempts to go in-depth into the codebase and involves interdependencies to analyze certain system specifics.
Profitable structuring
In the SOA system, all services are clearly mapped, and all business layers are logically structured and organized. This results in enabling the enterprise of any size to respond more dynamically to issues and changes in both technical and business aspects. Things become that much easier when you can take a certain brick and remove it or replace it with another without undermining the whole system.
No mono
The fact that SOA system services are separate and neatly structured means more efficient and convenient testing where one can easily narrow down problem areas and track particular issues. This is a lifesaver for businesses that are tired of putting a major effort into testing, debugging, and maintaining monolithic software structures.
What are the fundamental approaches to modernize legacy systems? Legacy System Modernization Approaches: Practical Advice on Dealing with Outdated Software 
Migrating Legacy Applications: Challenges in Service-Oriented Architecture
In order to achieve all the above-mentioned benefits of SOA for legacy systems, naturally, one first has to handle the legacy software architecture migration to SOA, which has its specifics and pitfalls. But if you know about the main challenges you are to face and how to get over them, the whole thing can go much simpler and hassle-free. The main factors affecting success in the migration of legacy systems to service-oriented architecture include the following.
Picking the right migration strategy
The first major challenge is understanding what exact parts of the legacy system you can/must/should move and how exactly you should do that. This requires thorough analysis and planning, during which you outline the components and objects that:
- can be left unchanged and moved as they are;
- should be rewritten or re-engineered from scratch in a new environment;
- can be safely replaced with new assets and objects;
- can be wrapped within a new interface.
Big systems can become too chunky to transfer
As much as the logical subdivision into services is a great way to make things lighter and simpler to manage, breaking down a huge system into tons of separate services brings new complications to the table. Thus, using too many services can significantly slow down the overall system performance. This is the major challenge of migrating a large-scale legacy application to SOA.
Managing all the moving parts
With multiple separate services lying at the core of one’s system, more individual management and maintenance are required, which can become a challenge. In particular, you have to thoroughly manage every service, translate every message they exchange and handle the bandwidth to achieve a sturdy service orchestration layer (which is essential for the whole SOA system’s success).
Replatforming is another effective approach to modernize your software. Find out What Is Legacy System Replatforming and When to Consider It
5 Tips for a Successful Migration of Legacy Systems to SOA Environments
Forewarned is forearmed, as they say, or “buyer beware,” as others say. Migrating to and configuring your legacy systems in SOA, you get all the chances not to risk any extra costs or profits, or business reputation if you know specifics from the start. Here are some pro-tips to help you with that.
#1 Run the Proof-of-concept
When it comes to legacy systems, you already know how exactly your system works, its ins and outs, operational properties, and other specifics. What you don’t know, though, is how it would work in a completely new environment. This is where the proof-of-concept stage helps avoid many complications and achieve adequate results in migrating the legacy solution to the SOA environment.
The PoC stage usually implies working on small transformation iterations and developing the essential functionality pieces to be seamlessly tested and put into the foundation of further system expansion. Taking it step by step and verifying the proper operation of each revamped element helps make the most fruitful SOA migration decisions.
How to test a legacy codebase without breaking anything? Learn here. Testing Legacy Codebase: What is, Common Problems and Best Practices
#2 Go beyond standard software deployment and create an organizational culture to support SOA
The migration of legacy systems to SOA environments is a task that goes beyond your regular software deployment routine. Particularly, preparing the ground for the process, you should analyze a) the underlying development methodology; b) software design techniques; and c) business relationships with customers, suppliers, and partners (if there are any).
In terms of the development and maintenance approach, it is logical to focus on achieving the post-migration infrastructure that your in-house or outsource team can figure out hassle-free. Just to prepare for the future, it is also good to use common, popular tools and languages. The same goes for the software design specifics.
Then, surely it is important to keep everybody involved with your software in line with the post-migration changes. This includes notifying and preparing users (both frontend users and administrators, support specialists, etc.), shareholders, partners, customers (potential or existing), suppliers, and others.
#3 Use metrics for seeing the efficiency of migration
Certain KPIs or key performance indicators can help you evaluate the whole reasonability of your migration to SOA. These can include:
- Time-to-market (SOA’s services reusability should help accelerate this);
- Application usage;
- Service quality;
- Security;
- Cost reduction and efficiency.
It’s your call how exactly to measure these KPIs. There are plenty of specialized tools just for this available online, and you can also consult with specialized vendors. In a nutshell, you need to capture the results your system used to bring as a legacy product for future comparisons. Then, you start capturing and analyzing sales, traffic, profits, load accumulation, etc., after the migration and look at what grows and what doesn’t.
How to choose a qualified legacy modernization partner? Firstly, ask these 9 Questions to Validate Your Legacy Modernization Vendor Before Starting the Cloud Migration Process
#4 Choose a tech stack based on specifics
The ultimate choice of tech stack for migration to SOA depends heavily on numerous underlying specifics of your product. It is best to involve people who worked on it or at least maintained it for some time who can recommend the most appropriate tools and frameworks. Ultimately, the tech stack must be reliable and future-friendly (i.e., optimized for future changes, renovations, and improvements).
#5 Prepare the legacy software for new user conditions
Preparations from the first pro-tip go both ways. Thus, a migrated system should be prepared for a new number of users beforehand (and better make a safety margin here). For this, it is best to define the maximum of concurrent and named users in terms of strict SLAs. If there is a possibility, it is best to settle this moment with your legacy modernization vendor.
#6 Watch your governance compliance
Portfolio specifics, third-party contractor nuances, and other governance structures are affected by the migration as much as any other related aspect. That’s why they must be reviewed and extended over all the fields, people, and regulations affected by migrating legacy systems to SOA.
What does it take to re-architect a software system? Where should you start first? Consider These Things Before Legacy Application Re-architecting
Consider ModLogix as Your Trusted Legacy Modernization Service Vendor
ModLogix is a specialized legacy modernization company that can help make integrating legacy software into a service-oriented architecture process next to effortless. We take outdated, clunky software systems and turn them into real business boosters that have been just sitting under the hood of your enterprise.
Consult right now for free!
Final Thoughts
Better software flexibility, more service convenience, and smoother performance — these are the major factors that increasingly motivate businesses to use SOA for legacy systems. The SOA approach to rebuilding legacy software may as well become the ultimate answer to your timely software renovation question. The two essential things to let you painlessly handle the whole thing — basic knowledge of how processes should run on the whole and a reliable, experienced modernization vendor by your side.
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